1. Field
The following description generally relates to flow control valves.
2. Description of Related Art
Flow control valves are used in many applications in which it is desirable to control the flow of fluid in a device or system. Examples of flow control valves are directional check valves, flow restricting valves and dispensing valves.
A directional check valve is biased in a closed configuration in which a sealing member prevents fluid flow through the valve, and the sealing member is moveable to place the valve in an open configuration in which the sealing member permits fluid flow through the valve in only a desired direction. More specifically, sufficient pressure from fluid flowing in the desired direction forces the sealing member to move to open the valve, allowing the fluid to flow through the valve in the desired direction. Backward fluid flow (“backflow”) in a direction opposite the desired direction while the valve is open forces the sealing member to move to close the valve.
One type of flow restricting valve allows fluid to flow therethrough in two opposing directions. The valve is biased in a closed configuration in which a sealing member permits a relatively small amount of backflow through the valve. The sealing member is moveable to place the valve in an open configuration in which a relatively large amount of fluid flow is permitted through the valve in a desired direction. Backflow opposite the desired direction while the valve is in the open configuration forces the sealing member to move to close the valve. The controlled backflow allowed through the valve while the valve is in the closed configuration may prevent fluid from being trapped in an area forward of the valve for extended periods of time when there is no fluid flow in the forward direction.
A dispensing valve includes a control mechanism for selectively opening the valve. The valve may be biased in a closed position in which a sealing member prevents fluid flow through the valve. The control mechanism may be operated to move the sealing member to open the valve and allow fluid flow through the valve in a desired direction.
The various flow control valves described above are often complex and expensive to manufacture. For example, some flow control valves may open and/or close too slowly, or may have sealing members that do not provide consistent, reliable sealing to prevent or restrict fluid flow.
Accordingly, it is desirable to provide flow control valves that are inexpensive to manufacture and provide improved performance.